Boeing's 787 Dreamliner jet has had a lot of troubles lately -- namely with its batteries -- and the last person the aerospace company likely wanted advice from was competitor Elon Musk.

Musk, the CEO of automaker Tesla and private space transport company SpaceX, recently told Flightglobal that the 787 Dreamliner's batteries are "inherently unsafe." His company SpaceX competes with the Boeing/Lockheed Martin partnership, United Launch Alliance, in the aerospace sector.

"Unfortunately, the pack architecture supplied to Boeing is inherently unsafe," said Musk.
"Large cells without enough space between them to isolate against the cell-to-cell thermal domino effect means it is simply a matter of time before there are more incidents of this nature. Moreover, when thermal runaway occurs with a big cell, a proportionately larger amount of energy is released and it is very difficult to prevent that energy from then heating up the neighboring cells and causing a domino effect that results in the entire pack catching fire."

However, Mike Sinnett, Boeing's 787 chief project engineer, defended the design and development of the batteries.

"I design a cell to not fail and then assume it will and then ask the next 'what-if' questions," said Sinnett. "And then I design the batteries that if there is a failure of one cell it won't propagate to another. And then I assume that I am wrong and that it will propagate to another and then I design the enclosure and the redundancy of the equipment to assume that all the cells are involved and the airplane needs to be able to play through that."

Musk's Tesla uses batteries fueled by lithium cobalt oxide, which is what Boeing uses for the 787. Musk understands that these batteries have highly flammable tendencies, and even offered his help to Boeing in its construction, but Boeing declined.

"They [Boeing] believe they have this under control, although I think there is a fundamental safety issue with the architecture of a pack with large cells," said Musk. "It is much harder to maintain an even temperature in a large cell, as the distance from the center of the cell to the edge is much greater, which increases the risk of thermal runaway."

In a recent report by The New York Times, it was discovered that Boeing knew about the battery fire issues in the 787 before this month's problems occurred, which grounded the jets in the U.S., Japan and India.

The report said that Japanese airline All Nippon Airways (ANA) replaced 10 787 batteries from May to December of 2012. Reasons included an unexpectedly low charge in the main battery, batteries that failed to start normally and one battery showing an error reading.

Japan Airline (JAL) also had "several cases" where it had to replace the 787's batteries before the issues that occurred this month, but it didn't disclose an exact number.

The airlines said they reported the incidents' to Boeing, but Boeing felt they didn't need to alert safety regulators because it was not considered a safety issue, but rather "within the scope of regular maintenance" carried out by airline crews.

I think the idea is that there isn't enough insulated separation between the packs to keep them from having a domino effect and there isn't enough cooling to cool each pack individually.

However the statement from Boeing saying that they designed them not to fail, so there isn't a reason to design safe insulation between the packs is ludicrous. Lithium batteries are inherently unsafe and all possible safety precautions should be taken.

quote: However the statement from Boeing saying that they designed them not to fail, so there isn't a reason to design safe insulation between the packs is ludicrous.

That is not at all what the Boeing designer said.

"I design a cell to not fail and then assume it will and then ask the next 'what-if' questions," said Sinnett. "And then I design the batteries that if there is a failure of one cell it won't propagate to another . And then I assume that I am wrong and that it will propagate to another and then I design the enclosure and the redundancy of the equipment to assume that all the cells are involved and the airplane needs to be able to play through that."

Emphasis added. Clearly you stopped reading after the first few words.

Good find on the pictures, but the picture of the battery cell/pack in the brochure looks quite a bit different than those pictured good bad picture.

In fact, I guess the circuit board in the case monitors each cell as you can see larger lugs and wires for the pack series and pos/neg terminals, but you can also see smaller ones as well going from each cell to the plug socket on the circuit board.

It likely monitors charge/discharge rates and voltage for each cell, but the question is if each of the cells have a thermal monitor as well...or if it did, was the controller board able to shut the whole pack down in time before the cell got hot enough to short circuit.